The present invention relates to cathartics which contain derivatives of prostaglandins.
Prostaglandins (hereinafter referred to as PGs) is the name of the group of fatty acids which possess various physiological activities and contained in human and animal tissues and organs. PGs basically contain the prostanoic acid skeleton of the following formula: ##STR1## and some synthetic products may contain the above skeleton with some modification.
PGs are classified into several types according to the structure and substituents on the five-membered ring, for example, ##STR2## and the like. Further, they are classified into PG.sub.1 s containing a 5,6-single bond: ##STR3## PG.sub.2 s containing, a 5,6-double bond: ##STR4## and PG.sub.3 s containing 5,6- and 17,18-double bonds: ##STR5##
PGs are known to have various pharmacological and physiological activities, for example, vasodilation, inducing of inflammation, platelet aggregation, stimulating uterine muscle, stimulating intestinal muscle, anti-ulcer effect and the like.
On the other hand, PGs having a 13,14-single bond and a C-15 constituting carbonyl group, and those having a 13,14-double bond and a C-15 constituting carbonyl group are found to exist in human or animal metabolites. These 13,14-dihydro-15-keto-prostaglandins and 15-keto-prostaglandins (hereinafter referred to as 15-keto-PGs) are known to be naturally produced metabolites by enzymatic metabolism of the corresponding PGs in vivo. These 15-keto-PGs have been reported to hardly exhibit various physiological activities that PGs possess and be pharmacologically and physiologically inactive metabolites [see, Acta Physiologica Scandinavica, 66, p.509- (1966)].
While estimating the pharmacological activities of the derivatives of 15-keto-PGs, however, the present inventors have found the derivatives substituted by one or more halogen atoms at the C-16 position, especially, fluorine atoms cause strong cathartic effect according to enteropooling test and the like, and have attained the present invention.